Is Scoria Felsic or Mafic?  (ANSWERED)

This article analyzes scoria rock’s chemical and physical features and supports its classification as an intermediate rather than mafic or felsic rock.

Is Scoria Felsic or Mafic? (EXPLAINED)


Scoria is a dark-colored, vesicular intermediate igneous rock that lacks crystals.

Although the rock’s minor mineral composition and physical appearance suggest that it is more mafic, the silica level of 50% exceeds the mafic maximum limit of 45 percent.

Also known as volcanic glass, scoria is made up of intermediate andesite and mafic basalt and has a dark shade that ranges from purplish red to black or dark brown.

Characteristics of Scoria

Physical Characteristics

Scoria rock is formed when magma’s gas expands to form bubbles that remain after lava solidifies.

The rock is often found in regions near active volcanoes, such as the Italian Alps and the Canary Islands.

The majority of scoria rocks are composed of intermediate andesite and mafic basalt.

Due to the existence of vesicles, scoria is heavier than pumice yet has a lower density.

Additionally, the rock’s walls are thicker, and its vesicles are larger than those of pumice.

The vesicular and aphanitic features imply the presence of several huge gas cavities.

Because the rock is available in a variety of colors, buyers have the choice of selecting red, brown, or black material.

While pumice floats owing to a larger concentration of trapped bubbles, scoria sinks.

A hand lens may be used to observe the small mineral crystals in the rock.

Certain scoria appear red due to iron oxidation of the basaltic lava after an eruption.

Chemical Composition

Scoria, also known as scoriaceous basalt, is a kind of basalt that contains 10% calcium oxide and 50% silica.

Additionally, scoria’s mineral composition is thought to be predominantly glass.

Other elements include sodium bicarbonate and potassium bicarbonate, quartz, magnetite, ilmenite, hornblende, hematite, biotite, apatite, olivine, pyroxene, and plagioclase.

Uses of Scoria

Scoria has a wide range of applications.

It is usually mined near the volcanic vents that appear as cone-shaped structures.

Scoria-filled volcanic explosions typically last just a few minutes and cover a very small area.

After an eruption, the dried aggregate of scoria is usually light in weight.

Therefore, it is often used in drainage and landscaping projects.

Further, some individuals use it in gas BBQ grills as well.

Other applications include traction aid on ice and snow-covered highways and high-temperature insulation.

Furthermore, the Rapanui people sculpted the topknots of most statues on Eastern Island out of red-colored Scotia.

The scoria was extracted from the Puna Pau quarry on the island.

Felsic or Mafic (Explained)

Depending on its silica concentration, a rock is classified as mafic or felsic.

A rock with less than 45% silica content is classified as mafic, whereas one with a silica content of more than 65% is classified as felsic.

If the silica content of rock is between 45% and 65%, it is classified as an intermediate.

Along with silica, felsic rocks are rich in feldspar.

Mafic rocks, on the other hand, are iron and magnesium-rich.

Rhyolite is a good example of a felsic rock, while basalt is a mafic rock.

It is necessary to classify a rock as mafic or felsic to indicate the possibility of a rock having certain mineral compositions.

As established, mafic rocks are more likely to contain iron and magnesium minerals, while felsic rocks contain silicon, aluminum, and potassium minerals.

In addition, these minerals are employed industrially, making it easy to establish their location depending on geological activities.

Is Scoria Felsic or Mafic?

Scoria is classified as an intermediate rock due to its 50% silica content, dark physical qualities, and acidic-alkaline chemical makeup.

In the classification, intermediate rocks include between 45 and 65 percent silica and may exhibit some mafic or felsic physical or chemical properties.

The rocks contain a mixture of intermediate andesite and mafic basalt.

Conclusion/ Outro

Scoria is a type of intermediate igneous rock created when gas-filled magma erupted due to volcanic activity.

Before the gas escapes, the rock solidifies, resulting in the solidification of bubbles that create the rock’s elongated chambers.

Although scoria is comparable to pumice, a felsic rock, scoria is darker and denser.

The red variety of scoria is caused by the oxidation of the rock’s iron component.

The rock’s 50% silica content characterizes it as an intermediate rock, as it contains other components such as potash, soda, and calcium oxide.

This chemical composition of the scoria makes it regarded as predominantly glass.

Due to the rock’s lighter properties resulting from trapped air, it is preferred for high-temperature insulation.

Additionally, it is used in landscaping and drainage works and on gas barbeque grills.

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Is Scoria Felsic or Mafic